- #1
themadhatter1
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Homework Statement
Write the Trigonometric Expression as an algebraic expression.
cos(2arccos 2x)
Homework Equations
Probably the inverse properties, I'm not sure.
The Attempt at a Solution
I know I can rewrite this equation as.
u= arccos 2x
cos(2cos u=2x)
I can also say that the adjacent leg is 2x units long and the hypotenuse is 1 unit long. Then using the pythagorean theorm I can figure the opposite leg to be sqrt(1-4x2)
I'm not sure If this is necessary though can someone point me in the right direction? The 2 in front of the arccos is throwing me off because if that wasn't there I would just use the inverse property and cos(arccos 2x) would equal 2x.